A first virtual machine executing in a first computer server is replicated to a second virtual machine executing in a second computer server, which is connected to the first computer server over a network. Virtual disks of the first virtual machine are transmitted to the second server, where each transmitted virtual disk corresponds to one of the virtual disks of the second virtual machine, the virtual disks of the first virtual machine having a format different from the format of the virtual disks of the second virtual machine. A plurality of updates to the virtual disks of the first virtual machine is captured, and contiguous data blocks from the virtual disks of the first virtual machine that are subject to the captured updates are identified. The identified contiguous data blocks are then transmitted to the second server for storage in the virtual disks of the second virtual machine.